This POWRE award will advance Dr. Murphy's professional career by helping her establish a new, independent line of investigation in an important area of research, the neural mechanisms of mammalian reproductive behavior. The goal of the research is to elucidate the neural mechanisms by which specific forebrain, brainstem and spinal cord sites coordinate male reproductive behavior. The medial preoptic (MPO) area of the forebrain plays a pivotal role in male reproductive behavior; however, this region does not project to the lumbosacral (L6/S1) spinal cord levels where the nerves are located that control sexual reflexes. Dr. Murphy's preliminary studies suggest a potential pathway that mediates forebrain influences on L6/S1 levels of the spinal cord. The lateral paragigantocellularis (LPGi) and gigantocellularis pars alpha (GiA) in the ventrolateral medulla receive direct input from the MPO and project heavily to the L6/S1 cord. In addition, the LPGi/GiA have been shown to potently modulate male reproductive behavior. The experiments to be conducted during the POWRE award will test the hypothesis that MPO efferents target LPGi and GiA neurons that project to the L6/S1 cord, and will provide the first anatomical, functional, and physiological characterization of the MPO--LPGi/GiA--spinal cord pathway. Currently, only fragmentary information exists regarding the neural pathways and physiological mechanisms mediating the forebrain's influence on spinal-cord sexual reflexes. Dr. Murphy's research, by closing this gap, will advance our understanding of regulation of mammalian reproductive behavior by the central nervous system.